fix LLP64 issue with python bser.c on windows
fix LLP64 issue with python bser.c on windows

Also need to check for negative overflow

dhruvsinghal/watchman,kwlzn/watchman,dcolascione/laptop-watchman,nodakai/watchman,wez/watchman,wez/watchman,wez/watchman,dhruvsinghal/watchman,dcolascione/laptop-watchman,dhruvsinghal/watchman,wez/watchman,dhruvsinghal/watchman,wez/watchman,facebook/watchman,nodakai/watchman,dcolascione/laptop-watchman,nodakai/watchman,facebook/watchman,wez/watchman,kwlzn/watchman,dhruvsinghal/watchman,dhruvsinghal/watchman,dcolascione/laptop-watchman,nodakai/watchman,dcolascione/laptop-watchman,kwlzn/watchman,kwlzn/watchman,wez/watchman,facebook/watchman,kwlzn/watchman,facebook/watchman,wez/watchman,facebook/watchman,nodakai/watchman,nodakai/watchman,dcolascione/laptop-watchman,nodakai/watchman,facebook/watchman,nodakai/watchman,dhruvsinghal/watchman,kwlzn/watchman,facebook/watchman,facebook/watchman,wez/watchman,dcolascione/laptop-watchman,kwlzn/watchman,facebook/watchman,dhruvsinghal/watchman,dcolascione/laptop-watchman,nodakai/watchman